[Diy_efi] Thermal barrier coatings

[Greg Hermann]

At 8:38 AM 1/21/03, John Stricker wrote:
>Greg,
>
>Weigh in on something for me, if you would.
>
>I've heard from several places that Teflon is not the way to go.  Teflon
>repels oil (along with everything else) and it's so slippery that the oil
>will not stay on it.  Moly disulfide is the second most popular coating, and
>it retains oil.  Now all of this is from people trying to sell me something,
>of course, and the Teflon advocate folks are quick to point out that if
>Teflon is THAT slippery what do you care if it sheds the oil?  A good
>question.  But then again, if Teflon works that well, why not coat
>everything with it and not run any oil at all??

Sorry I got to the other post first, John.

The Nimet coatings are NOT at all JUST teflon--more like some teflon in a
matrix. Teflon is soft. Hard anodizing and carbide are, needless to say,
VERY hard. Just enough teflon in the matrix to make the surface slippery,
but NONE of the easy to scratch characteristics of just a teflon coating.

One is quite likely better off with the NiMet teflon/hard anodizing on a
4032 alloy forged piston rather than a 2618 alloy one--although less
ductile, the 4032 is harder, and thus will give a better, less likely to
deform substrate for the teflon/anodizing !!

I think the unpredictabilty of the diy coatings lies in the
unpredictability of diy surface prep  and process !!

HPC is my choice for GOOD, CONSISTENT thermal barrier coatings.

Greg
>
>I think you get where I'm going here.  I've decided to do the moly disulfide
>route and we'll see how that goes.  I chose that after talking to the guys
>at Swain, who have a lot of experience with coatings over a lot of years
>and, in fact, even used to offer Teflon coatings themselves.
>
>I've tried some of the DIY coatings with highly variable results.  Sometimes
>very good, sometimes not good at all.  The problem is that there was no way
>to tell ahead of time what the results were going to be, and I really don't
>want to find out after it's blowing pieces of the coating out the exhaust
>ports.  I'll leave the coating to the pros for now, at least on internal
>components.
>
>John Stricker
>----- Original Message -----
From: "Greg Hermann" <bearbvd at mindspring.com>
>To: "List for general do-it-yourself EFI talk" <diy_efi at diy-efi.org>
>Sent: Tuesday, January 21, 2003 8:10 AM
>Subject: Re: [Diy_efi] Thermal barrier coatings
>
>
>> At 3:52 AM 1/21/03, Ohio Benz wrote:
>>
>> Among the more interesting coatings I have come acrross are from Ni-Met
>> Industries (Gary, Ind.)
>>
>> They do a teflon impregnated anodizing (RC 70 surface hardness and _VERY_
>> slippery) which is neat for pistons (skirts, pin bores and ring grooves).
>>
>> Also, a teflon impregnated carbide coating (also very hard and slick) for
>> brass/bronze/copper alloys which might be pretty interesting for the ID of
>> valve guides and possibly also for con rod small end bushings.
>>
>> Greg
>>
>> >Tech Line Coatings sells a full range of ceramic, dry
>> >film lube and other coatings for temp barrier
>> >applications.
>> >I have applied the ceramic to piston tops and would
>> >recommend that you also do the combustion chambers and
>> >valve heads. BTW I applied this to forged pistons.
>> >The application seems simple enough, but proper
>> >cleaning, grit blasting and access to an industrial
>> >oven for 600F baking is required.  It took me several
>> >tries to get a thick enough coating as recommended
>> >without it flaking after high temp curing,
>> >They have header, brake caliper and a variety of other
>> >coatings capable of withstanding very high temps.
>> >If anyone would like a pic of a finished piston or
>> >combustion chamber contact me offline.
>> >
>> >=====
>> >Jerrit Ekama
>> >
>> >OHB Tuning
>> >Custom fabrication of performance parts for your Mercedes, VW, BMW, Audi.
>> >U.S. domestic and foreign vehicle repair and maintenance.
>> >Powder coating, Anodizing, TIG welding, CNC machining services.
>> >IM: OHBenz
>> >
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